Question: Which of these numbers is composite? ${17,\ 23,\ 29,\ 33,\ 37}$
Explanation: A composite number is a number that has more than two factors (including 1 and itself). 17, 23, 29, and 37 each have only two factors. The factors of 33 are 1, 3, 11, and 33. Thus, 33 is the composite number.